I used to use it. month ago, this thread came up, and they talked me into using it again. So I bought 4 of the purigen bags, loaded them up with purigen, and put one in each of my filter socks. it got super brown really fast, because it sits in a filter sock with all the gunk from the tank. my water is still a touch cloudy. but it's a 540 gallon tank, sand is still kinda new, maybe i'm a little on the low side on pump output (2 max-flo 2400's), i don't know. i think purigen is great for some things (like tannins from new driftwood), ineffective for other things. so it depends on what's in your water as to how big a fan you are of purigen. i'm lukewarm to the stuff?
It is definitely cleanable. drop it in bleach, it turns off-white again, that's cool.